Irrigation systems for plant bedding environments, or for use in other applications calling for low-profile or soil-direct hydration, are available in a variety of forms. The simplest type of bedding irrigation system uses a perforated, or water permeable, end-capped "soaker" hose for delivering water directly to the soil along the length of the hose. This method has the benefit of allowing the horticulturist, farmer or nursery worker to place the irrigation source adjacent to numerous sites needing hydration which are configured in a spatially nonuniform array.
Another well known form of irrigation system for bedding and low crop environments uses a series of drip or spray fittings coupled to small diameter tubing. Typically, an irrigation system of this type, i.e. a coupled fitting system, includes several meters or more of tubing distributed over a large area of the surface to be irrigated. The tubing may be made to bend or branch by means of U, L or T-shaped connectors, to provide coverage over a greater surface of the irrigated area.
The drip or spray devices employed in coupled fitting irrigation systems may be in-line, or attached to multiple hose segments at their termini. Drip type fittings are relatively simple devices, typically consisting of a small plastic drip attachment coupled to the conduit by means of a male fitting, and elevated above the surface to be irrigated by a ground support device. The drip attachment has a small aperture from which fluid drips directly downward to the soil surface, coupled with an internal means of regulating fluid pressure to achieve a suitable pressure and flow rate from the aperture.
A widely used drip fitting which employs these concepts is the Pressure Compensating Dripper manufactured by Raindrip.RTM., 21305 Itasca Street, Chatsworth, Calif. 91311. The Raindrip.RTM. drippers are terminal or in line, disc-shaped fittings, having an eccentric aperture on one face of the disc from which the fluid drips. These devices also have an internal pressure governing means whereby flow from the aperture occurs at 1/2, 1, or 2 gallons per hour (gph), depending on which model of dripper is used. The Raindrip.RTM. dripper is positioned above the surface to be irrigated by means of a plastic stake having a tapered lower end for anchoring the stake in soil, and a ring or c-shaped head for receiving standard bedding irrigation conduit. The principal advantage of drip fittings for bedding irrigation is that, because hydration of the irrigated surface is generally confined to the immediate area surrounding the fitting, these devices allow for more spatially precise irrigation. Drip devices may be placed directly adjacent to or above particular sites requiring irrigation, such as the bases of individual plants, thereby avoiding wasteful irrigation of unplanted surface areas.
The second type of device commonly used in coupled fitting irrigation systems is the spray or sprinkler fitting. Spray fittings generally consist of a small plastic spray attachment coupled to the conduit by means of a male connecter, and elevated above the surface to be irrigated by a ground support device. Spray devices feature a number of advantages over drip type fittings. Most importantly, spray fittings generally possess means for directing fluid flow from an aperture laterally, i.e. horizontal to the irrigated surface, and under substantial pressure. Accordingly, spray fittings typically provide a broader surface area of irrigation coverage than drip fittings.
Spray fittings come in two general forms, static spray fittings and rotary spray fittings. Static spray fittings typically spray fluid over a fixed, wedge or fan-shaped area of the irrigated surface. Different models of static spray fittings cover broader or narrower areas, ranging from a small wedge-shape to a full circular spray pattern. An example of a static spray fitting which generates a sub-circular spray pattern is the Rain-Mister.TM. manufactured by Raindrip.RTM.. This device is disc-shaped and has a narrow, central, laterally directed aperture from which pressurized fluid escapes in approximately a semicircular spray pattern. Raindrip.RTM. also makes a Low Volume 1/4-Circle sprayer, which, as the name indicates, generates approximately a 1/4 circular spray pattern. The Raindrip.RTM.1/4 circular sprayer is a simple device having a vertically directed aperture from which pressurized fluid escapes and impinges on a curved, overhanging hood. The back and top of the hood break up the escaping flow into a lateral spray pattern, while confining the lateral spray pattern to an area matching the acutely angled, laterally facing opening of the hood.
In addition to static spray devices for coupled fitting type irrigation systems, at least one type of rotary sprinkler is manufactured for this use. Raindrip.RTM. makes a full-circular rotary sprinkler fitting which closely resembles rotary sprinkler fittings employed in larger scale applications, eg. rotary lawn sprinklers. The Raindrip.RTM. rotary sprinkler has a swiveling head with two diametrically opposed apertures running from the center to the periphery of the head. The head is mounted on a central, hollow fitting which is connected to a pressurized fluid source. Fluid passes through the central fitting into the central openings of the apertures. The apertures are oriented with their longitudinal axes in a non radial position with respect to the head, so that the pressurized fluid running through the apertures exerts torque on the sprinkler head, causing it to rotate. As the sprinkler head rotates, spray from the external openings of the apertures, which themselves emit a sub-circular spray pattern, covers a full-circular area around the sprinkler head.
Several drawbacks attend the use of both conventional drip and spray fittings for plant bedding and low crop irrigation systems. Perhaps the most significant of these problems is that neither type of fitting is readily adjustable in terms of flow direction. Drip fittings are non-directional, in the sense that fluid delivery is strictly oriented downward due to gravity, and hydration therefore only occurs around the base of the fitting or its ground support. Spray fittings on the other hand may be directional, but their directionality is static, or non-adjustable. In other words, spray fittings which direct a sub-circular, or directional, spray pattern may be oriented at the time of their placement so that their spray is directed, for example, toward a particular plant, or away from an edge or corner of a bedding table or crop row. This directional capacity may avoid wasteful overspray of non-targeted surfaces and provide for more precise irrigation of discrete sites requiring hydration. Such discrete irrigation may not be as readily accomplished using a network of full-circular spray units, which may unnecessarily irrigate spaces between plants, causing excessive fluid consumption.
A major drawback of static directional spray fittings, however, is that once they are installed into a bedding environment a worker can only change their spray direction by manually removing and repositioning the fitting and/or its ground support. This in turn may require the labor-intensive task of repositioning an entire section or portion of a network of fittings interconnected by conduit and coupling devices. Accordingly, the lack of directional adjustability of conventional irrigation fittings may greatly reduce the efficiency of daily irrigation adjustments, as well as more substantial irrigation changes, for example to accommodate new plantings, growth stages and topographical or environmental regimes.
A second major drawback to using conventional drip and spray fittings in plant bedding and low crop environments, is that both types of fittings lack flow rate adjustability. These conventional attachments cannot be individually adjusted to provide different flow rates, even though separate models may be manufactured to individually provide discrete flow rates. Accordingly, a horticulturist, farmer or nursery worker must undertake the laborious task of switching hundreds or thousands of fittings to accommodate the distinct irrigation needs of various species, environmental regimes, or growth phases of plants. Alternatively, accessory devices, such as regulatory valves, may be employed to provide adjustable flow rates in a coupled fitting irrigation system. However, it would be very expensive to provide flow adjusting valves for each drip unit employed in a bedding or low crop irrigation system. Accordingly, to provide the most flexible irrigation system in terms of flow adjustability would generally be cost prohibitive.
A third important shortcoming of using conventional drip and spray fittings in plant bedding and low crop irrigation is that they tend to become clogged by mineral deposits and other contaminants. This clogging is largely attributable to the small apertures through which fluid vents, either as spray or drip flow, from the pressurized source. Because of the small diameter of the apertures, mineral deposits and other contaminants can stick and accumulate until clogging of the aperture occurs. In addition, clogging of conventional drip and spray fittings is attributable to the absence of moving, cleanable parts in the aperture design of such devices.
A final drawback to conventional spray and drip fittings is that each of these types of devices possess unique benefits and flaws which are not found in the other type of device. Drip fittings, because they are placed adjacent to individual plants, provide for precise delivery of fluid to individual subjects. However, this generally imposes a one-fitting/one-subject limitation. On the other hand, spray fittings, due to their laterally directed, pressurized spray pattern, can deliver fluid to a much larger surface area. This same feature may be undesirable when a bedding or low crop environment includes unplanted areas or areas where overspray is otherwise undesirable. In addition, unlike a drip fitting, a spray fitting typically sprays over and beyond the base of the fitting or its ground support, so that the area immediately below and surrounding the fitting typically does not receive irrigation. Accordingly, in order to accomplish full coverage irrigation using spray fittings, it is generally necessary to overlap patterns of multiple fittings to cover the areas below and surrounding each fitting.
On the basis of these considerations, a need exists in the plant bedding and low crop irrigation industry for an inexpensive irrigation system which is adaptable for irrigating narrow or broad areas, and which provides for rapid, easy adjustability of irrigation flow rate and direction. A further need exists for a plant bedding and low crop irrigation system which can provide different spray patterns to accommodate spatial, topographical and other restrictions, and which resists clogging.